Hi EthanHE,

Sorry that you are facing the brightness on your room at night but in sb8200 we don't have the option to change or adjust the brightness on the front panel of the led lights. 

If you have any other queries on sb8200 let us know.

Put a blanket over the modem at night.

I’ve used electric tape before. The blanket is a little bit of a poor choice as it’ll trap heat. 

The SB8200v2 i just installed has an option to turn off the Lights on the configuration page.

In this case we would suggest you to try the same option on the modem interface after disconnecting the coax cable from the modem to make it work, you can give this a try.